Streaming APRS data over XMPP

12 Jul 2014

This blog post is more than two years old. It is preserved here in the hope that it is useful to someone, but please be aware that links may be broken and that opinions expressed here may not reflect my current views. If this is a technical article, it may no longer reflect current best practice.

I’ve recently started playing with radios again and I’ve been looking mainly at packet radio. APRS is a system which uses amateur radio to transmit position reports, weather reports, and messages between users. There is an Internet backbone for APRS called APRS-IS that can be used to access a filtered feed of APRS broadcasts. I thought it would be nice if such a feed were also available via XMPP so set about building a gateway.

This was not as easy as I’d hoped it would be. All the libraries I tried to use to access APRS-IS data either were in a language I didn’t want to touch (i.e. Perl) or wouldn’t run on my system without segfaulting. Luckily, it is quite easy to talk to the APRS-IS servers as it turns out. Opening a TCP connection and sending:

user MM6MVQ-1 pass -1 vers testsoftware 1.0_05 filter r/57.1526/-2.1100/50\r\n

caused the server to begin sending me all the APRS packets broadcast within 50km of Aberdeen.

Next up was the XMPP bit. I really wanted to get a pubsub service going, but I had no idea how they worked, and after fighting with libraries again and even giving up on the server software and using jabber.ccc.de’s server instead I went for the easier option of just sending messages to a MUC for now.

Check out xmpp:aprs-aberdeen@conference.jabber.ccc.de?join to see the messages being broadcast around me.

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Streaming APRS data over XMPP

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